Cisco SGE2000P Administration Guide - Page 21

Chapter Linksys One Ready Communications Solution 3 Stack Master The unit assigned the Unit ID number 1 serves as the Stack Master. All other units are stack members. The Stack Master provides a single point of control, configuration and management for the entire stack, and stores the configuration for all stack members. (Members do not store any configuration information.) Stack Backup Master The unit assigned the Unit ID number 2 is a special stack member that serves as the stack Backup Master. A stack Backup Master assumes the role of Stack Master for the remaining stack members if the stack Master fails or is disconnected. The Stack Master stores a copy of the active configuration on the Backup Master. This copy is used only if the Backup Master assumes the role of Stack Master. NOTE: Only the configuration file is copied. Any dynamically-filled tables (for example, learned addresses) are not copied from the Stack Master to the Backup Master. If the Backup Master assumes the role of Stack Master, it builds its own dynamic tables. Stack Members The units assigned the Unit IDs 3 through 8 are called stack members. A stack member operates only as a member of the stack under the direction of an operational Stack Master (or a Backup Master that has assumed the Stack Master role). Stack members are not directly manageable and configurable, and must be managed through the Stack Master. They do not contain any meaningful configuration information, including their own configuration. If an operational Stack Master is not present and reachable, these units are not functional. Master-Enabled Units Units that are assigned a Unit ID number of 1 or 2 are called master-enabled units. Only master-enabled units participate in the Master Election process (see below) when they are initialized, are inserted into a new stack, or lose connectivity with the existing Stack Master. Only master-enabled units participate in the Master Election process and can become the Stack Master or Backup Master. (Units that are assigned a Unit ID of 3 through 8 can only Chapter 3: Connecting the Switch 16 Understanding Advanced Stacking